Problem registering on my new computer

I have moved all files from my Mac G4 to my new Mac G5. However, I now have a problem in launching ThinkTanks. The program asks for my "Registration Code from purchase order confirmation e-mail". My ignition key is listed but there is no registration code listed in my confirmation eMail. I have gone on-line to my account at GarageGames but can find only my order number (41420) and ignition key ( 4KYY-M6PZ-BRAA-MMCW). Neither of these satisfy ThinkTanks' registration page. I note that just under the space for entering the registration code, ThinkTank displays the following information: "Offline registration ID: 2ZHW-WCY4-AC2D". I tried this too, but it also doesn't work.

ThinkTanks was working perfectly before moving to my new computer and it has become a favorite game with my family on-line. I have purged all files on the old G4. What must I do to re-register the game on my new computer?